WCOP 2000, held in conjunction with ECOOP 2000 in Sophia Antipolis, France, was the fifth workshop in the successful series of workshops on component-oriented programming. The previous workshops were held in conjunction with the respective ECOOP conferences in Linz, Austria, Jyväskylä, Finland, Brussels, Belgium and Lisbon, Portugal. WCOP96 had focused on the principal idea of software components and worked towards definitions of terms. In particular, a high-level definition of what a software component is was formulated. WCOP97 concentrated on compositional aspects, architecture and gluing, substitutability, interface evolution, and non-functional requirements. WCOP98 had a closer look at issues arisingin industrial practice and developed a major focus on the issues of adaptation. WCOP'99 moved on to address issues of component frameworks, structured architecture, and some bigger systems built using components frameworks. The topics for WCOP 2000 focused on component composition, validation and refinement and the use of component technology in the software industry.